Machine gun selectively operated by a gas or recoil system



Nov. l2, 1963 J. l.. LocHHl-:AD

MACHINE GUN SELECTIVELY OPERATED BY A GAS OR RECOIL SYSTEM Filed April 5, 1962 5 Sheets-Sheet l MACHINE GUN SELECTIVELY OPERATED BY A GAS 0R REcoIL SYSTEM Filed April 5, 1962 Nov. 12, 1963 J. l.. LocHHl-:AD

3 Sheets-Sheet 2 INVENTOR.

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MACHINE GUN SELECTIVELY OPERATED BY A GAS OR RECOIL SYSTEM l Filed April 5, 1962 3 Sheets-Sheet 3 (D rfi IIO INVENTOR. Inl-Ln L lnlfhheul United States Patent O 3,110,221 MACHINE GUN SELECTIVELY OPERATED BY A. GAS R RECQIL SYSTEM John L. Loclihead, Springfield, Mass., assigner to the United States `of America as represented by the Secretary of the Army Filed Apr. 5, 1962, Ser. No. 185,485 8 Claims. (Cl. 89-159) (Granted under Title 35, U.S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes Without the payment to ine of any royalty thereon.

This invention relates to machine guns `and more particularly to the operating mechanisms thereof.

There are two principal systems .for utilizing the energy produced by discharge of rounds ina machine gun to actuate those mechanisms which feed, fire and eject the rounds. One system uses energy of the generated gases to power the mechanisms and the other utilizes the recoil energy produced in the barrel when a round is discharged therein.

The advantages and the disadvantages of both systems are well known in the art Iand need not be noted lhere except to point out that gas systems are preferred where guns are to be hand fired or fired from a tripod because the recoil action transferred to. the gun support is less violent than with recoil systems. However, gas systems are undesirable when the guns are to be fired from inclosed areas as in tanks and aircraft because of the noxious gases which are vented from the gas systems during firing operation.

It is, therefore, the object of this invention to provide a universal machine -gun which may 'be selectively operated by a gas system or a recoil system merely by rotating a Iselector switch and which may be hand fired or fired from a remote station, with the machine gun being simple but rugged in construction and positive in operation.

The specific nature of the invention as well as other objects and advantages lthereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

FIG. 1 is a longitudinally cross-sectioned view of the rear section of the machine gun showing the gun adapted for hand ring and set for gas operation and the bolt in the forward locked position;

FIG. 1A is the forward extension of FIG. 1 and shows the selector set for gas operation;

FIG. 2 is a fragmentary elevational View showing the selector switch set for gas operation;

FIG. 3 is a view similar to IFIG. 1 showing the relationship of the parts when the bolt assembly is adjacent recoil position during the recoil stroke;

FIG. 4 is a View taken along line 4--4 of FIG. 1A;

FIG. 5 is a view taken along line 5-5 of FIG. 4;

FIG. 6 is a View taken -along line 6-6 of FIG. 3;

FIG. 7 is .a longitudinally cross-sectioned view of the rear section of the machine gun showing the gun adapted for remote firing and set for recoil operation and showing the relationship of the parts when the carrier begins to move relative to the bolt by action of the accelerator during recoil movement of the bolt assembly;

FIG. 7A is the forward extension of FIG. 7 and shows the selector set for recoil operation of the machine gun;

FIG. 8 is a view similar to FIG. 2 -but showing the selector fswitch set for recoil operation;

FIG. 9 is a view taken along line 9-9 of FIG. 7A;

FIG. 10 is a view taken along line 10--10` of FIG. 9; and

FIG. 11 is a perspective view of the selector.

j 3,119,221 Patented Nov. l2, 1963 Fice Shown in the figures is a machine gun 12 for automatically firing small caliber rounds 14 of 7.62 mm. size or the like. Machine gun 12 includes a receiver 16 in which a bolt assembly 18 is mounted for sliding reciprocation between a forward locked position and a rearward recoil position. A barrel assembly 2i) is journalled in the front end of receiver 16 for longitudinal reciprocation between a forward battery position and a rearward driving position.

Barrel assembly 20 includes a barrel 22 the front portion of which extends forwardly from receiver 16 and a gas cylinder 4assembly 24 which includes a gas cylinder 26 and a cooperating piston 28. Gas cylinder 26 is fixedly mounted on barrel 22 approximately midway the length thereof so as to be disposed within the front end of receiver 16. Piston 28 is slidingly mounted in a bore 30 which extends forwardly into gas cylinder 26 from the rear end thereof to lan end wall 32. A transverse bore 34 extends through gas cylinder 24 forwardly of end wall 32 and matingly receives a cylindrical selector 36 for 90 rotation between `a first position and a second position. Selector 36 is provided with an arcuate channel 3S which extends peripherally around approximately one-fourth the circumference Ithereof. When selector 36 is in the first position, channel 38 provides communication between a fir-st gas port 40 extending longitudinally between end wall 32 yand bore 34- and a second gas port 42 which extends vertically between such bore and the bore of barrel 22. When selector 36 is rotated 90 in a counterclochwise direction tothe second position, channel 38 provides communication between first gas port 411 and an orifice 44 which extends vertically between bore 34 and the -bottom of gas cylinder 24.

Selector 36 extends from gas cylinder 24 on opposite sides thereof to form extending portions 46 and such extending portions are each bifurcated by a rectangular slot 48 which is longitudinally disposed when the selector is in the second position and which forms at each end a pair of locking lugs 50.

Extending inwardly from opposite sides of receiver 16 is a pair of longitudinal flanges 52 which have a crosssectiona-l configuration similar to that of the slots 48 and which are arranged so as rto be received by the slots to permit longitudinal reciprocation of barrel assembly 20 when selector 36 is in the second position. When selector 36 is in the first position, the locking lugs 50 are respectively in butting relationship with the front end of flanges 52, noted -at l54, to block rearward displacement of barrel assembly 20 from battery position. A pair of lugs 56 extend into receiver 16 for respective longitudinal alignmenrt with the flanges 52 and are spaced forwardly therefrom so that Ithe rear ends thereof, noted at 58, have butting relationship with locking lu-gs 50i `when barrel assembly 2li` is in battery position.

Selector 36 is manually rotated between 'the first and second positions by a switch 60' which includes a cylindrical shaft 62 rotatingly received by a mating hole 64 in the right-hand side of receiver 16. Hole `64 is located so that shaft 62 is in axial alignment with selector 36 when barrel assembly 20 is in battery posit-ion. Provided on the inner end of shaft 62 is a tongue 66 which is matingly receivable by slot 48 in the adjacent end of selector 36 when barrel assembly 20ji is in battery position and selector 36 is in the second position.

Provided on the outer end of shaft 62 is ra lever 68 for manually rot-ating shaft 62, and thereby `selector 36 through the engagement of tongue 66 with the cooperating slot 48. Switch 60 is indexable in a position which is coincident with the first position of selector 36 and which is identifiable by lever 68 pointing to a marking of Gas on the outside of receiver 16. Switch 60 is yalso i-ndexable in a position which is coincident with the second position of selector 36 and which is identifiable by lever 68 pointing to a marking of Recoil on receiver 16.

When lever 68 points to the Gas marking, communication is provided by channel 38 between the bore of barrel 22 and the inside of gas cylinder 26 and slots 48 are vertically disposed to position locking lugs 50 in Iblocking relationship respective to flanges 52 so that barrel assembly is blocked in Abattery position. When lever 63 points to Recoil, locking lugs 52 are out of locking relationship relative to flanges 52 and slots 48 are longitudinally disposed for receiving `the flanges to permit `displacement of barrel assembly to and from the driving position, and channel 38 is positioned to permit the vent-ing of bore 30 forwardly of piston 28 out of orifice 44. Barrel `assembly 2b is biased to the battery position by a pair of coiled compression springs 67.

Bolt assembly 1S perfonms the conventional functions of moving rounds 14 from Va feeding mechanism 69 to the chamber of barrel 22, supporting the chambered round for discharge and ejecting the spent case from receiver 16 `and includes a slide 76, a bolt 72, and a tiring pin 73 received `by a mating bore in the lbolt for longitudinal and rotational displacement. Slide 70 is of yoke configuration and is provided with a pair of laterally spaced arms '74 and an integral operating rod 76 Iwhich extends forwardly in axial alignment with piston 28 so as to be in contact therewith, whereby, the slide is `accelerated rearwardly by the piston when energized by gases `bled from barrel 22. Extending between the rear ends of the arms 74 is a crosspiece 7S which projects thereabove so that a longitudinal aperture 30 through the crosspiece is in coaxial alignment with the bore of barrel 22.

Bolt 72 is essentially cylindrical in configuration and is mounted in `aperture 80 for rotation between a lock and an unlock positon and for relative longitudinal dispiacement respective to slide 761. Provided on the front end of bolt 72 is a pair of diametrically opposed lugs 52 which are rotatable in front of cooperating lugs 84 on the breech end of barrel 22 when the bolt is rotated to the lock position, to lock the lbolt to the barrel. When bolt 72 is in the unlock position, lugs 82 thereon are cle-ar of lugs 84 on barrel 22, permitting rearward displacement of `the bolt relative to the barrel. Bolt 72 is rotatable `between the lock and unlock positions by conventional means including a pin 86 which extends through mating holes in crosspiece 78 and firing pin 73 and through a cam slot 90 in the bolt so that the longitudinal displacement of slide 70 relative to the bolt, after the bolt is stopped in forward flight by contact with barrel 22, is converted to rotational displacement of the bolt from the unlocked to the locked position and firing pin 73 is projected forwardly from the front face of Athe bolt. During rearward displacement of slide 7 0 relative to bolt 72, the bol-t is rotated to the unlock position and firing pin 73 is retracted thereinto. Bolt 72 is releasably lockable in an extended position relative to slide 70 by conventional means (not shown).

An accelerator 92 of conventional design and function -is pivotally mounted on a transversal pin 94 through the bottom of receiver 16 so as to extend upwardly between the front end of slide 70 :and an actuating boss 93 depending from `barrel 22. When barrel assembly 2? is energized for rearward displacement to the driving position, the arcuate contiguration of accelerator 92 and its relationship with ybarrel 22 and slide 70 causes the slide to `accelerate faster than the barrel resulting in relative displacement between the slide and bolt 72, which is locked to the barrel, until the bolt is unlocked by the relative displacement. W'hen barrel assembly 20 reaches the driving position, bolt 72 is unlocked from Ibarrel 22 and accelerator 92 drives bolt assembly 1S to the recail position. Bolt assembly 1S is `biased to its forward position -by a pair of coil springs 96 which act against slide 76 and are compressed thereby during recoil travel.

Machine gun 12 fires from the open bolt position and, therefore, -bolt assembly 18 is seared when in the recoil position. Provision is made to either sear bolt assembly 18 by means of a trigger mechanism housed in a pistol grip 100 removably mounted underneath receiver 16 or by means of a solenoid lactuated trigger mechanism mounted in a housing 104 replaceably mounted on the rear end of the receiver. Trigger mechanism in pistol grip |100 includes a Sear 166 which is engageable with la sear notch 108 formed in the underside of slide 70 adjacent 4the lfront end thereof. The trigger mechanism i-n solenoid housing 194 includes a Sear 110 which is engageable with `a scar notch 112 formed in the underside of slide 70 adjacent the rear end thereof.

When machine gun 12 is to be hand tired, pistol grip 115i! is installed on receiver 16 and a shoulder piece 114 installed on the rear end thereof. When machine `gun 12 is to be tired from a remote station, pistol grip 100; is removed and solenoid housing y104 replaces shoulder piece 114.

When machine gun 12 is to be operated by gas energy, switch 60 is rotated to where lever 68 points to Gas, whereby, selector 36 is rotated to the first position wherein channel 38 extends between first gas port 4t) and second gas port 42 and locking lugs 50 are in lblocking relationship respective to flanges 52 to lock 4barrel 22 in `battery position. Machine gun 12 is fired Iby actuation of the firing mechanism in pistol grip 109 or in solenoid housing 104, which ever is selectively mounted in receiver 16. This releases bolt assembly 13 which is propelled forwardly to its forward position under the compulsion of springs 96. During its forward travel, bolt :assembly 118 picks up a round 14 from' feeding mechanism 69 and transfers the round into the 4chamber of barrel 22. When the forward travel of bolt 72 is stopped by the enga-ged lround 14 being fully chambered, slide 76 continues forwardly to lcause locking of the bolt relative to barrel 22 and the projection of firing pin 73 from the bolt to discharge the cham-bered round.

Gas energy from the discharge enters second gas port 42, after the round projectile has passed thereby, and iS directed by channel 3S through first gas port 4t) into gas cylinder 26. The gas energy vented into gas cylinder 26 energizes piston 2S for rearward displacement against slide 70 which is propelled rearwardly thereby. Duringl the initial rearward travel of slide 70, it travels relative to bolt 72, which is locked to barrel 22, until the bolt is rotated to the unlock position. Then, the rearward travel of slide 7l) is transferred to bolt 72 and both travel rearwardly together, causing extraction and ejection of the case of the fired round 14 according to conventional means which are not a part of this invention.

When machine gun 12 is to be operated by the recoil energy transferred to barrel 22 by the discharge of round 14 therein, switch 60 is rotated to where lever 68 points to RecoiL Consequently, channel 38 is positioned to vent gas cylinder 26 forwardly of piston 28 through orifice 44, and slots 4S are in alignment with flanges 52. When bolt assembly 2% is released to re a round 14, as hereinbefore described, the energy from the discharge causes barrel 22 to recoil rearwardly. As gas cylinder assembly 24 is xedly attached to barrel 22, the gas cylinder assembly with selector 36 therein moves rearwardly with the barrel. Consequently, selector 36 leaves engaging cooperation with tongue 66 and slots 48 are received by fianges 52. During initial recoil travel of barrel assembly 20, bolt 72 is locked thereto and then, during continued travel to driving position, accelerator 92 speeds up the travel of slide 70 relative to barrel 22 and this relative displacement causes rotation of the bolt to the unlock position. By the time that barrel assembly 20 reaches driving position, bolt 72 is unlocked from barrel 22 so that bolt assembly 13 is free to be propelled to recoil position by accelerator 92 and barrel assembly 20 immediately returns to battery position with slot 4S on the right end of selector 36 receiving tongue 66 to re-engage switch 60 to selector 36.

Among the many advantages of such a universal type machine gun is that, if either the gas system or the recoil system should become inoperative, the machine gun might be able to be operated from the other system. This could be very important in combat conditions.

From the foregoing it is clearly apparent that there is provided here a machine gun which is readily adapted for use with diierent types of mounts and in different types of weapon carrying vehicles by being selectively operable by both a recoil and a gas system and which is simple but rugged in construction and positive in operation.

Although a particular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following claims are intended to include such variations.

I claim:

1. A machine gun including a receiver, a bolt assembly mounted in said receiver for longitudinal reciprocation, a barrel mounted in said receiver for longitudinal reciprocation between a forward battery position and a rearward driving position, a gas system for actuating said bolt assembly responsive to gas pressure generated by the discharge of round in said barrel, said gas system including a gas cylinder tixedly mounted on said barrel for reciprocation therewith, a recoil system for actuating said bolt assembly responsive to recoil energy produced in said barrel by the discharge of rounds therein, and a selector disposed in cooperation with said gas system and said recoil system so as to select one thereof for the actuation of saidvbolt assembly.

2. The machine gun as defined in claim 1 wherein said gas system includes a bore in said gas cylinder and a piston slidingly mounted in said bore for actuation against said bolt assembly responsive to gas pressure received by said bore, and wherein said selector is mounted in said gas cylinder for displacement therewith.

3. The machine gun as dened in claim 1 wherein said receiver includes a pair of internal flanges, said selector includes means cooperating with said flanges for blocking recoil of said barrel from battery position when said selector is positioned to select said gas system for bolt assembly actuation, and said selector also includes means for directing gases from said barrel to said gas cylinder.

4. The machine gun as defined in claim 1 wherein said selector is mounted in said gas cylinder for displacement therewith, said receiver is provided with a pair of internal ilanges, and said selector includes locking lugs respectively arranged for contact with said flanges to block recoil of said barrel from the battery position when said selector is positioned to select said gas system for bolt actuation and slots respectively disposed for receiving said flanges to permit reciprocation of said barrel to and from the driving position when said selector is positioned to select said recoil system for bolt actuation.

5 The machine gun as defined in claim 4 wherein said selector is arranged for rotation in said gas cylinder between a rst position wherein said gas system is selected for actuation of said bolt assembly and a second position wherein said recoil system is selected for actuation of said bolt system.

6. The machine gun as defined in claim 5 wherein said means in said selector for directing gases from said barrel to said gas cylinder when said selector is actuated to select said gas system for actuation of said bolt assembly includes a peripheral channel extending in a arc around said selector, said channel being arranged so as to provide communication between a first gas port cornmunicating with said bore in said gas cylinder and a second gas port communicating with the bore of said barrel when said selector is positioned to select said gas system for bolt assembly actuation, said channel being arranged to provide communication between said second gas port and an oriiice extending through said gas cylinder to vent said bore in said gas cylinder to outside atmosphere when said selector is positioned to select said recoil system for bolt assembly actuation, and wherein said selector is arranged to block communication between said rst gas port and said second gas port when said selector is positioned to Select said recoil system for bolt assembly actuation.

7. The machine gun as defined in claim 5 wherein said selector is laterally disposed through said gas cylinder and is arranged to extend on opposite sides thereof to form a pair of extending ends and said locking lugs and said slots are formed in the extending ends, and including a` switch rotatably mounted in said receiver for cooperation with said selector to provide means for the manual rotation thereof between the lirst and second positions.

8. The machine gun as defined in claim 7 wherein said switch is positioned in said receiver so as to be cooperable with said selector when said barrel is in the battery position, and wherein said switch is provided with a tongue receivable by said one of said slots adjacent to said switch when said barrel is in battery position, said tongue being arranged so as to be in longitudinal alignment with the adjacent one of said flanges whenvsaid switch is rotated to position said selector in the second position.

References Cited in the le of this patent UNITED STATES PATENTS 2,956,481 Barr et a1. oct. 18,' 1960 

1. A MACHINE GUN INCLUDING A RECEIVER, A BOLT ASSEMBLY MOUNTED IN SAID RECEIVER FOR LONGITUDINAL RECIPROCATION, A BARREL MOUNTED IN SAID RECEIVER FOR LONGITUDINAL RECIPROCATION BETWEEN A FORWARD BATTERY POSITION AND A REARWARD DRIVING POSITION, A GAS SYSTEM FOR ACTUATING SAID BOLT ASSEMBLY RESPONSIVE TO GAS PRESSURE GENERATED BY THE DISCHARGE OF ROUND IN SAID BARREL, SAID GAS SYSTEM INCLUDING A GAS CYLINDER FIXEDLY MOUNTED ON SAID BARREL FOR RECIPROCATION THEREWITH, A RECOIL SYSTEM FOR ACTUATING SAID BOLT ASSEMBLY RESPONSIVE TO RECOIL ENERGY PRODUCED IN SAID BARREL BY THE DISCHARGE OF ROUNDS THEREIN, AND A SELECTOR DISPOSED IN COOPERATION WITH SAID GAS SYSTEM AND SAID RECOIL SYSTEM SO AS TO SELECT ONE THEREOF FOR THE ACTUATION OF SAID BOLT ASSEMBLY. 